Canui Canvas User interface

Hello All,

Some days ago I was looking for some points in the area of Canvas ,I found
this web site:http://canui.sourceforge.net/examples/index.html

A web site for designing user interface via Canvas.I view the source of this
page I didn't find Canvas tag,but when I used Developert Tools of google

Chrome I saw Canvas Tag! what was the reason and what's your opinion about
it?

Best Regards

-- 
Paniz Alipour